DOCSLIB.ORG

Cuyamaca Rancho State Park

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Cuyamaca Rancho State Park GEOLOGICAL GEMS OF CALIFORNIA STATE PARKS | GEOGEM NOTE 49 Cuyamaca Rancho State Park Peninsular Ranges Batholith The Cuyamaca Rancho State Park lies within the Peninsular Ranges geomorphic province of southern California, Features/Process: which is characterized by a series of northwest trending Petrology of the roots of ancient mountains and valleys that are similar in trend to the San mountains on an exotic terrane Andreas Fault system that lies to the east. The Peninsular along the plate boundary Ranges are chiefly made up of coarsely crystalline igneous rock, termed the Peninsular Ranges Batholith. The events that formed the batholith are complex, but clues to its formation can be gathered from an analysis of geology of the park and surrounding region. Without question, it is the grinding of the North American plate sliding past the Pacific plate known as the San Andreas Fault system that is currently controlling the landforms of the region. But this has been occurring for a relatively brief period Cuyamaca Rancho State Park GeoGem Note 49 Why it’s important: The rounded hills of granitic and metamorphic rock of the Peninsular Ranges are the deep roots of a much different ancient range that included volcanoes and high mountains possibly like the Andes. By examining these roots, we learn about the internal workings of other mountains. of geologic time. Before this fault started to rip the state apart, California was the scene of a major mountain building events, which occurred during the Mesozoic era. These mountain building events, known as the Nevadan and Sevier Orogenies, were the result of the collision and subduction of the Farallon oceanic plate beneath the North American continental plate. A modern analogy to this event is that of the Andes Mountains of South America. There, the Andes are constructed of active and inactive volcanoes fed from magma due to the subduction of the Nazca oceanic plate below the South American continental plate. The geologic record of these mountain building events is evident in the Cuyamaca Rancho State Park area as the Triassic-Jurassic Julian Schist, and the Jurassic and Cretaceous metamorphic and igneous rocks. The following sections discuss those rocks and the implications to the formation of the batholith. Mountain-Building Events and the Rock Record Around 165 million years ago, during the Jurassic Period of the Mesozoic Era, the west coast of North America was being subjected to intense volcanic activity. The supercontinent Pangaea was breaking apart and the North American plate was carrying the continent toward the west as it still does today. The Pacific Ocean floor (oceanic crust) broke into several plates, including the Farallon plate, and was pushed under North America. The subducted plates melted at depth beneath the continental margin. Southern California was in a different geographic location, off the coast of the current Mexican mainland and submerged. Many volcanoes formed far to the east GEOLOGICAL GEMS OF CALIFORNIA STATE PARKS PENINSULAR RANGES GEOMORPHIC PROVINCE Cuyamaca Rancho State Park GeoGem Note 49 What you can see: A series of granitic and metamorphosed sedimentary rocks that represent past mountain building events. along the western margin of the continent creating a volcanic island arc. Sediment and volcanic rocks eroded from the volcanic highlands to the east were deposited in the ocean basins to the west. Further volcanism occurred later in two pulses during the Cretaceous period, which possibly consisted of volcanic islands being formed offshore, where magma erupted and cooled into andesite and basalt. As the continuing plate collision occurred along the western margin, the island volcanoes were moved east and shoved up against the North American continent. The resulting collision compressed and squeezed existing igneous and sedimentary rocks, causing them to be metamorphosed. The constant compression also caused them to be pushed up into huge mountains. Since then, the great mountains have been eroded to their cores. What Rocks Can Be Seen? During the mountain building events, volcanoes generated abundant quantities of volcanic rocks. However, these were not the only rocks that were deposited. As some of the magma was trapped below the volcanoes, it cooled beneath miles of overlying rock and sediment. These masses of rock that cooled deep in the earth’s crust are Jurassic granodiorite, Cretaceous gabbro and Cretaceous monzogranite. These rocks, along with other similar “granitic” rocks, form the Peninsular Ranges Batholith. The Jurassic rocks are the cores of the ancient volcanoes, and the remnants of sand, GEOLOGICAL GEMS OF CALIFORNIA STATE PARKS PENINSULAR RANGES GEOMORPHIC PROVINCE Cuyamaca Rancho State Park GeoGem Note 49 mud and volcanic debris deposited in the ocean basins. These rocks appear layered or banded because they were subject to immense heat and pressure causing the minerals to orient themselves in response to the pressure. Some of the Cretaceous rocks in the park area also represent the cores of ancient volcanoes, but a slightly different type. The Cretaceous Cuyamaca gabbro, a dark crystalline rock, has been interpreted to be the core of an island volcanic system. The Chiquito Peak monzogranite is much lighter in color and was emplaced around the time of the gabbro, and may represent the partial melting of the continental crust as the magma and island arc system slammed into the North American continent. The Cuyamaca gabbro and Chiquito Peak monzogranite can be observed in the vicinity of the Cuyamaca Rancho State Park Interpretive Center. Final Thoughts As a fragment of continent caught on the oceanic plate heading northward toward Alaska, this exotic terrane will undergo many more profound changes. Will it ever make it there before erosion obliterates all vestiges? Written by Jeremy Lancaster, California Geological Survey Photos: Janis Hernandez Prepared by California Geological Survey, Department of Conservation | www.conservation.ca.gov/cgs for California State Parks | www.parks.ca.gov Geological Gems of California State Parks, Special Report 230 – Fuller, M., Brown, S., Wills, C. and Short, W., editors, 2015 Geological Gems of California, California Geological Survey under Interagency Agreement C01718011 with California State Parks..
Load more

Recommended publications
  • 3.6 Geology and Soils
    3. Environmental Setting, Impacts, and Mitigation Measures 3.6 Geology and Soils 3.6 Geology and Soils This section describes and evaluates potential impacts related to geology and soils conditions and hazards, including paleontological resources. The section contains: (1) a description of the existing regional and local conditions of the Project Site and the surrounding areas as it pertains to geology and soils as well as a description of the Adjusted Baseline Environmental Setting; (2) a summary of the federal, State, and local regulations related to geology and soils; and (3) an analysis of the potential impacts related to geology and soils associated with the implementation of the Proposed Project, as well as identification of potentially feasible mitigation measures that could mitigate the significant impacts. Comments received in response to the NOP for the EIR regarding geology and soils can be found in Appendix B. Any applicable issues and concerns regarding potential impacts related to geology and soils that were raised in comments on the NOP are analyzed in this section. The analysis included in this section was developed based on Project-specific construction and operational features; the Paleontological Resources Assessment Report prepared by ESA and dated July 2019 (Appendix I); and the site-specific existing conditions, including geotechnical hazards, identified in the Preliminary Geotechnical Report prepared by AECOM and dated September 14, 2018 (Appendix H).1 3.6.1 Environmental Setting Regional Setting The Project Site is located in the northern Peninsular Ranges geomorphic province close to the boundary with the Transverse Ranges geomorphic province. The Transverse Ranges geomorphic province is characterized by east-west trending mountain ranges that include the Santa Monica Mountains.
    [Show full text]
  • The Coastal Scrub and Chaparral Bird Conservation Plan
    The Coastal Scrub and Chaparral Bird Conservation Plan A Strategy for Protecting and Managing Coastal Scrub and Chaparral Habitats and Associated Birds in California A Project of California Partners in Flight and PRBO Conservation Science The Coastal Scrub and Chaparral Bird Conservation Plan A Strategy for Protecting and Managing Coastal Scrub and Chaparral Habitats and Associated Birds in California Version 2.0 2004 Conservation Plan Authors Grant Ballard, PRBO Conservation Science Mary K. Chase, PRBO Conservation Science Tom Gardali, PRBO Conservation Science Geoffrey R. Geupel, PRBO Conservation Science Tonya Haff, PRBO Conservation Science (Currently at Museum of Natural History Collections, Environmental Studies Dept., University of CA) Aaron Holmes, PRBO Conservation Science Diana Humple, PRBO Conservation Science John C. Lovio, Naval Facilities Engineering Command, U.S. Navy (Currently at TAIC, San Diego) Mike Lynes, PRBO Conservation Science (Currently at Hastings University) Sandy Scoggin, PRBO Conservation Science (Currently at San Francisco Bay Joint Venture) Christopher Solek, Cal Poly Ponoma (Currently at UC Berkeley) Diana Stralberg, PRBO Conservation Science Species Account Authors Completed Accounts Mountain Quail - Kirsten Winter, Cleveland National Forest. Greater Roadrunner - Pete Famolaro, Sweetwater Authority Water District. Coastal Cactus Wren - Laszlo Szijj and Chris Solek, Cal Poly Pomona. Wrentit - Geoff Geupel, Grant Ballard, and Mary K. Chase, PRBO Conservation Science. Gray Vireo - Kirsten Winter, Cleveland National Forest. Black-chinned Sparrow - Kirsten Winter, Cleveland National Forest. Costa's Hummingbird (coastal) - Kirsten Winter, Cleveland National Forest. Sage Sparrow - Barbara A. Carlson, UC-Riverside Reserve System, and Mary K. Chase. California Gnatcatcher - Patrick Mock, URS Consultants (San Diego). Accounts in Progress Rufous-crowned Sparrow - Scott Morrison, The Nature Conservancy (San Diego).
    [Show full text]
  • Investigating Earthquake Hazards in the Northern Salton Trough, Southern California, Using Data from the Salton Seismic Imaging Project (SSIP)
    Investigating Earthquake Hazards in the Northern Salton Trough, Southern California, Using Data from the Salton Seismic Imaging Project (SSIP) G. S. Fuis1, J. A. Hole2, J. M. Stock3, N. W. Driscoll4, G. M. Kent5, A. J. Harding4, A. Kell5, M. R. Goldman1, E. J. Rose1, R. D. Catchings1, M. J. Rymer1, V. E. Langenheim1, D. S. Scheirer1, N. D. Athens1, J. M. Tarnowski6 Refraction Models Line 6 Line 7 Abstract 1 U.S. Geological Survey (USGS), Earthquake Science Center (ESC), Menlo Park, CA. The southernmost San Andreas fault (SAF) system, in the northern Salton Trough (Salton Sea and Coachella Valley), is considered likely to produce a large-magnitude, damaging earthquake in the 2 Virginia Polytechnic Institute and State University, near future. The geometry of the SAF and the velocity and geometry of adjacent sedimentary Dept. Geosciences, Blacksburg, VA basins will strongly influence energy radiation and strong ground shaking during a future rupture. The Salton Seismic Imaging Project (SSIP) was undertaken, in part, to provide more accurate infor- 3 California Institute of Technology, Seismological mation on the SAF and basins in this region. Laboratory 252-21, Pasadena, CA. We report preliminary results from modeling four seismic profiles (Lines 4-7) that cross the Salton 4 Scripps Institution of Oceanography, La Jolla, CA. Trough in this region. Lines 4 to 6 terminate on the SW in the Peninsular Ranges, underlain by Meso- From high-res zoic batholithic rocks, and terminate on the NE in or near the Little San Bernardino or Orocopia active-source seismic - 5 Nevada Seismological Laboratory, University of From 1986 North Palm ? modeling 8 km SE PC and Mz igneous Mountains, underlain by Precambrian and Mesozoic igneous and metamorphic rocks.
    [Show full text]
  • Fault-Rupture Hazard Zones in California
    SPECIAL PUBLICATION 42 Interim Revision 2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA Alquist-Priolo Earthquake Fault Zoning Act 1 with Index to Earthquake Fault Zones Maps 1 Name changed from Special Studies Zones January 1, 1994 DEPARTMENT OF CONSERVATION California Geological Survey STATE OF CALIFORNIA ARNOLD SCHWARZENEGGER GOVERNOR THE RESOURCES AGENCY DEPARTMENT OF CONSERVATION MIKE CHRISMAN BRIDGETT LUTHER SECRETARY FOR RESOURCES DIRECTOR CALIFORNIA GEOLOGICAL SURVEY JOHN G. PARRISH, PH.D. STATE GEOLOGIST SPECIAL PUBLICATION 42 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA Alquist-Priolo Earthquake Fault Zoning Act With Index to Earthquake Fault Zones Maps by WILLIAM A. BRYANT and EARL W. HART Geologists Interim Revision 2007 California Department of Conservation California Geological Survey 801 K Street, MS 12-31 Sacramento, California 95814 PREFACE The purpose of the Alquist-Priolo Earthquake Fault Zoning Act is to regulate development near active faults so as to mitigate the hazard of surface fault rupture. This report summarizes the various responsibilities under the Act and details the actions taken by the State Geologist and his staff to implement the Act. This is the eleventh revision of Special Publication 42, which was first issued in December 1973 as an “Index to Maps of Special Studies Zones.” A text was added in 1975 and subsequent revisions were made in 1976, 1977, 1980, 1985, 1988, 1990, 1992, 1994, and 1997. The 2007 revision is an interim version, available in electronic format only, that has been updated to reflect changes in the index map and listing of additional affected cities. In response to requests from various users of Alquist-Priolo maps and reports, several digital products are now available, including digital raster graphic (pdf) and Geographic Information System (GIS) files of the Earthquake Fault Zones maps, and digital files of Fault Evaluation Reports and site reports submitted to the California Geological Survey in compliance with the Alquist-Priolo Act (see Appendix E).
    [Show full text]
  • Nehrp Final Technical Report
    NEHRP FINAL TECHNICAL REPORT Grant Number: G16AP00097 Term of Award: 9/2016-9/2017, extended to 12/2017 PI: Whitney Maria Behr1 Quaternary geologic slip rates along the Agua Blanca fault: implications for hazard to southern California and northern Baja California Abstract The Agua Blanca and San Miguel-Vallecitos Faults transfer ~14% of San Andreas-related Pacific-North American dextral plate motion across the Peninsular Ranges of Baja California. The Late Quaternary slip histories for the these faults are integral to mapping how strain is transferred by the southern San Andreas fault system from the Gulf of California to the western edge of the plate boundary, but have remained inadequately constrained. We present the first quantitative geologic slip rates for the Agua Blanca Fault, which of the two fault is characterized by the most prominent tectonic geomorphologic evidence of significant Late Quaternary dextral slip. Four slip rates from three sites measured using new airborne lidar and both cosmogenic 10Be exposure and optically stimulated luminescence geochronology suggest a steady along-strike rate of ~3 mm/a over 4 time frames. Specifically, the most probable Late Quaternary slip rates for the Agua Blanca Fault are 2.8 +0.8/-0.6 mm/a since ~65.1 ka, 3.0 +1.4/-0.8 mm/a since ~21.8 ka, 3.4 +0.8/-0.6 mm/a since ~11.8 ka, and 3.0 +3.0/-1.5 mm/a since ~1.6 ka, with all uncertainties reported at 95% confidence. These rates suggest that the Agua Blanca Fault accommodates at least half of plate boundary slip across northern Baja California.
    [Show full text]
  • GEOPHYSICAL STUDY of the SALTON TROUGH of Soutllern CALIFORNIA
    GEOPHYSICAL STUDY OF THE SALTON TROUGH OF SOUTllERN CALIFORNIA Thesis by Shawn Biehler In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy California Institute of Technology Pasadena. California 1964 (Su bm i t t ed Ma Y 7, l 964) PLEASE NOTE: Figures are not original copy. 11 These pages tend to "curl • Very small print on several. Filmed in the best possible way. UNIVERSITY MICROFILMS, INC. i i ACKNOWLEDGMENTS The author gratefully acknowledges Frank Press and Clarence R. Allen for their advice and suggestions through­ out this entire study. Robert L. Kovach kindly made avail­ able all of this Qravity and seismic data in the Colorado Delta region. G. P. Woo11ard supplied regional gravity maps of southern California and Arizona. Martin F. Kane made available his terrain correction program. c. w. Jenn­ ings released prel imlnary field maps of the San Bernardino ct11u Ni::eule::> quad1-angles. c. E. Co1-bato supplied information on the gravimeter calibration loop. The oil companies of California supplied helpful infor­ mation on thelr wells and released somA QAnphysical data. The Standard Oil Company of California supplied a grant-In- a l d for the s e i sm i c f i e l d work • I am i ndebt e d to Drs Luc i en La Coste of La Coste and Romberg for supplying the underwater gravimeter, and to Aerial Control, Inc. and Paclf ic Air Industries for the use of their Tellurometers. A.Ibrahim and L. Teng assisted with the seismic field program. am especially indebted to Elaine E.
    [Show full text]
  • Southward Continuation of the San Jacinto Fault Zone Through and Beneath the Extra and Elmore Ranch Left-Lateral Fault Arrays, Southern California
    Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-2013 Southward Continuation of the San Jacinto Fault Zone through and beneath the Extra and Elmore Ranch Left-Lateral Fault Arrays, Southern California Steven Jesse Thornock Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Geology Commons Recommended Citation Thornock, Steven Jesse, "Southward Continuation of the San Jacinto Fault Zone through and beneath the Extra and Elmore Ranch Left-Lateral Fault Arrays, Southern California" (2013). All Graduate Theses and Dissertations. 1978. https://digitalcommons.usu.edu/etd/1978 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. SOUTHWARD CONTINUATION OF THE SAN JACINTO FAULT ZONE THROUGH AND BENEATH THE EXTRA AND ELMORE RANCH LEFT- LATERAL FAULT ARRAYS, SOUTHERN CALIFORNIA by Steven J. Thornock A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Geology Approved: ________________ ________________ Susanne U. Janecke James P. Evans Major Professor Committee Member ________________ ________________ Anthony Lowry Mark R. McLellan Committee Member Vice President of Research and Dean of the School of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2013 ii ABSTRACT Southward Continuation of the San Jacinto Fault Zone through and beneath the Extra and Elmore Ranch Left-Lateral Fault Arrays, Southern California by Steven J. Thornock, Master of Science Utah State University, 2013 Major Professor: Dr.
    [Show full text]
  • 1. Some Physiographic Aspects of Southern California ·~
    1. SOME PHYSIOGRAPHIC ASPECTS OF SOUTHERN CALIFORNIA ·~ BY ROBERT P. SHARP t Southern California is a land of physiographic abundances, con- are widespread, and it seems likely that they represent the same trasts, and peculiarities. The wide range of !!.'eological materials and episodes of geological history, although this has not been definitely structures, the considerable differences in rliinatic environments, the established. The late mature topography is termed the Sulphur host of geological processes at work, and the recency of diastrophic Mountain surface in the Ventura region (Putnam, 1942, p. 751 ) and, events are the principal factors responsible. less suitably, the Timber Canyon surface in Santa Clara Valley (Grant and Gale, 1931, p. 38). It developed rapidly on areas of rela­ PHYSIOGRAPHIC DIVISIONS tively soft Cenozoic rocks after the middle Pleistocene orogeny and Several good physiographic descriptions of southern California prior to late Pleistocene uplifts. are available (Hill, 1928, pp. 74-101; Fenneman, 1931, pp. 373-379, The Sulphur Mountain surface is probably younger than remnants 493-508; Gale, 1932, pp. 1-2, 8-10; Reed, 1933, pp. 1-23, 267-268; of an erosion surface or surfaces of even more gentle relief on areas Hinds, 1952, pp. 63-108, 185-215), and it seems pointless to add an­ of older crystalline rocks (W. J. Miller, 1928, p. 199). Many of these other by regurgitation of the same material. Readers interested in remnants were formerly attributed to the so-called Perris or southern the location, size, trend, and inter-relation of landscape features can California peneplain (Dickerson, 1914, pp. 259-260; English, 1926, p.
    [Show full text]
  • External Grant Award Nos. 08HQGR0032, 08HQGR0039, 08HQGR0042 and 08HQGR0045 DEVELOPMENT of a CALIFORNIA-WIDE THREE-DIMENSIONAL S
    External Grant Award Nos. 08HQGR0032, 08HQGR0039, 08HQGR0042 and 08HQGR0045 DEVELOPMENT OF A CALIFORNIA-WIDE THREE-DIMENSIONAL SEISMIC WAVESPEED MODEL: COLLABORATIVE RESEARCH WITH UW-MADISON, LDEO/COLUMBIA UNIV., U. C. SAN DIEGO, AND CALTECH Clifford H. Thurber Geology and Geophysics, University of Wisconsin-Madison 1215 W. Dayton St. Madison, WI 53706 Telephone: (608) 262-6027 FAX: (608) 262-0693 Email: [email protected] Peter M. Shearer IGPP 0225, University of California San Diego La Jolla, CA 92093-0225 Telephone: (858) 534-2260 FAX: (858) 534-5332 Email: [email protected] Felix Waldhauser Lamont-Doherty Earth Observatory, Columbia University P.O. Box 1000, Palisades, NY 10964 Telephone: (845) 365-8538 FAX: (845) 365-8150 Email: [email protected] Egill Hauksson California Institute of Technology Mail code 251-21, 1200E California Blvd. Pasadena, CA 91125 Telephone: 626-395-6954 FAX: 626-564-0715 Email: [email protected] External Grant Award Nos. 08HQGR0032, 08HQGR0039, 08HQGR0042 and 08HQGR0045 DEVELOPMENT OF A CALIFORNIA-WIDE THREE-DIMENSIONAL SEISMIC WAVESPEED MODEL: COLLABORATIVE RESEARCH WITH UW-MADISON, LDEO/COLUMBIA UNIV., U. C. SAN DIEGO, AND CALTECH Clifford H. Thurber Geology & Geophysics, Univ. of Wisconsin-Madison, 1215 W. Dayton St., Madison, WI 53706 Telephone: (608) 262-6027, FAX: (608) 262-0693 Email: [email protected] Peter M. Shearer IGPP 0225, University of California San Diego, La Jolla, CA 92093-0225 Telephone: (858) 534-2260, FAX: (858) 534-5332 Email: [email protected] Felix Waldhauser Lamont-Doherty Earth Observatory, Columbia University, P.O. Box 1000, Palisades, NY 10964 Telephone: (845) 365-8538, FAX: (845) 365-8150 Email: [email protected] Egill Hauksson California Inst.
    [Show full text]
  • Quaternary Rift Flank Uplift of the Peninsular Ranges in Baja and Southern California by Removal of Mantle Lithosphere
    TECTONICS, VOL. 28, TC5003, doi:10.1029/2007TC002227, 2009 Click Here for Full Article Quaternary rift flank uplift of the Peninsular Ranges in Baja and southern California by removal of mantle lithosphere Karl Mueller,1 Grant Kier,1 Thomas Rockwell,2 and Craig H. Jones1,3 Received 2 November 2007; revised 13 January 2009; accepted 12 May 2009; published 9 September 2009. [1] Regional uplift in southern California, USA, and and Rockwell, 1992; Muhs et al., 2002]. The cause of uplift, northern Baja California, Mexico, is interpreted to however, has not been studied in detail, nor has it appeared result from flexure of the elastic lithosphere driven particularly significant until the recognition of active blind largely by heating and thinning of the upper mantle thrust faults in offshore regions of the southern California beneath the Gulf of California and eastern Peninsular borderland by Rivero et al. [2000]. They attribute the Ranges. The geometry and timing of faulting in the observed coastal uplift in southern California to slip on a blind thrust system that includes one segment (the Ocean- Salton Trough and Gulf of California, the history of side detachment) extending downdip beneath the coastline, recent rock uplift along the Pacific coastline, and implying significant seismic hazard for this region. In geophysical data constrain models of lithospheric contrast, Johnson et al. [1976], Muhs et al. [1992] and heating and thinning based on unloading of a Orme [1998] have argued that regional uplift in coastal continuous elastic plate. High topography that marks southern California and northern Baja California is due to the 400-km-long rift shoulder in northern Baja aseismic tectonic or epirogenic processes Table 1.
    [Show full text]
  • Spatial Variations of Rock Damage Production by Earthquakes in Southern California
    Earth and Planetary Science Letters 512 (2019) 184–193 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl Spatial variations of rock damage production by earthquakes in southern California ∗ Yehuda Ben-Zion a, , Ilya Zaliapin b a University of Southern California, Department of Earth Sciences, Los Angeles, CA 90089-0740, United States b University of Nevada, Reno, Department of Mathematics and Statistics, Reno, NV 89557, United States a r t i c l e i n f o a b s t r a c t Article history: We perform a comparative spatial analysis of inter-seismic earthquake production of rupture area and Received 18 August 2018 volume in southern California using observed seismicity and basic scaling relations from earthquake Received in revised form 27 January 2019 phenomenology and fracture mechanics. The analysis employs background events from a declustered Accepted 3 February 2019 catalog in the magnitude range 2 ≤ M < 4to get temporally stable results representing activity during a Available online xxxx typical inter-seismic period on all faults. Regions of high relative inter-seismic damage production include Editor: M. Ishii the San Jacinto fault, South Central Transverse Ranges especially near major fault junctions (Cajon Pass Keywords: and San Gorgonio Pass), Eastern CA Shear Zone (ECSZ) and the Imperial Valley – Brawley seismic zone earthquakes area. These regions are correlated with low velocity zones in detailed tomography studies. A quasi-linear rock damage zone with ongoing damage production extends between the Imperial fault and ECSZ and may indicate fault zones a possible future location of the main plate boundary in the area.
    [Show full text]
  • South Coast and Montane Ecological Province
    Vegetation Descriptions SOUTH COAST AND MONTANE ECOLOGICAL PROVINCE CALVEG ZONE 7 March 30, 2009 Note: This Province consists of the Southern California Mountains and Valleys Section or "Mountains" (M262B) and the Southern California Coast Section or "Coast" (262B) Note the slope gradients as follows: High gradient or steep (greater than 50%) Moderate gradient or moderately steep (30% to 50%) Low gradient (less than 30%) CONIFER FOREST / WOODLAND DM BIGCONE DOUGLAS-FIR ALLIANCE Bigcone Douglas-fir (Pseudotsuga macrocarpa) - dominated stands are found in the Transverse and Peninsular Ranges from the Mt. Pinos region south. The Bigcone Douglas-fir Alliance is defined by the clear dominance of this species among competing conifers. It has been mapped sparsely in four subsections in the Coast Section, and infrequently in seven subsections and abundantly in four subsections of the Mountains Section. These pure conifer or mixed conifer and hardwood stands occur at lower elevations, generally in the range 1400 – 5600 ft (426 - 1708 m) in the Coast Section and up to about 7000 ft (2135 m) in the Mountains Section. Although mature individuals are capable of sprouting from branches and boles after burning, intense or frequently repeated fires and drought cycles will tend to eliminate this conifer. However, Bigcone Douglas-fir may become locally dominant with Canyon Live Oak (Quercus chrysolepis) as an associated tree on protected mesic canyon slopes, but not at the highest elevations. Sites in this Alliance are usually north facing at lower elevations and south-facing or steeper slopes at upper elevations. Shrub associates commonly include species of Ceanothus, Birchleaf Mountain Mahogany (Cercocarpus betuloides), California Buckwheat (Eriogonum fasciculatum), Chamise (Adenostoma fasciculatum), and shrub forms of the Live Oaks (Quercus spp.).
    [Show full text]